Electric brake system.



PATENTED JULY 14, 1903..

F. E. ICASE. ELECTRIC BRAKE SYSTEM.

APPLICATION FILED FEB. 19, 1900.

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VIEEIEEE- PATENTED JULY 14, 1903.

P. E. CASE.

, ELECTRIC BRAKE SYSTEM.

APPLICATION FILED FEB. 19', 1900.

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UNIT-ED STATES Patented. uly 14,

PATENT OFFICE.

FRANK E. CASE, OF SCI-IENECTADY, NEW YORK, ASSIGNOR TO THE GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

SPECIFICATION forming part f Letters Patent-N0. 733,900, dated. J 14, 1903.

Application iiled February 19,1900., Serial NeI 5,690. (Normcdelr) Y T0 @ZZ whom/lit may concern:

Beit known that '1, FRANK E. CASE, a citizen ofthe United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements'in Electric Brake Systems, of

t which the following is a specification.

-. state of the art to employ two or more motors My invention relates toa system of electric braking in which the dynamo-electric machine or machines which normally operate as motors driving theload are employed as momentuindriven generators, and lhas for its object to provide a novel and convenient application of this now Well-known system by which I am enabled to graduate the braking eect with great precision and also in case of an electric car or similar load prevent the reduction of braking eect by the slippi'tg of the car-wheels along the rails. y

In carrying out my invention I connect the dynamo-electric machine tothe' load to be braked by means of ,a magnetic clutch supplied with current from lany suitabley source, the said dynamo-electric machine being either electrically connected to a circuit containing resist-ance or else shortcircuited by a connection having practically no resistance, and I provide means for varying within any desired limits the energizing-current supplied to the magnetic clutch.

inasmuch as it is customary in the present as a motor in braking, according tothe degreel of magnetization ot the clutch. The dynamo-electric machines are electrically connected in series and are short-circuited through the magnetic clutch, a shunt-circuit'of variable resistance being provided for diverting' more or less of the current from the' energiz-l ing-winding of the clutch. The dynamo-electric machine, which is rigidly connected to the load, operates then as a generator to supply current to the magnetic clutch and at the same Vtime assists in retarding the load,while` the amount of retardation is determined by the force with' which the second dynamo-electric machine is clutched to its load.

It haszheretofore been attempted to retard a moving load--such as, for example, a car .or trainby means of a braking system comprising two dynamo-electric machines rigidly connected to the load and electrically connected in series, .so that both operate as monientuin-driven generators, and such a system would be very effective were it not for the fact that the braking eiect is liable to be suddenly reduced to a'minimum by the slipping ofthe wheels to which one of the dynamoelectric machines is connected. The electromotive force generated in the braking-circuit when the two dynamo-electric machines are connected in series is of course double what it would be if they were connected in multiple, and consequently the current-'how in the braking-circuit, as well as the braking effect, may be varied within wide limits; but with the two machines thus rigidly'connected to their respective car-'wheels the system is subject to the objection that whenever the current in the braking-circuit reaches such an amount that the torque of either of the dynamo-electric machines Voperating asa generator becomes greater than that which can be transmitted by the load through the rolling friction ofthe car= wheels the wheels to which, the said dynamoelectric machine is connected will begin to slip. The coefficient of friction is greatly diminished by such slipping, and, moreover, the

current flowing through the machine connected to the slipping Wheels lis-in the proper direction to'drive the said machine as a motor in a direction oppositeto that in which it has beenoperating as a generator. This machine is therefore liable to speed up as a motor and generate a counter electromotive force so considerable that the current flowing in the circuit of the d ynalno-electric machines will be reduced to a minimum andthe brakliiig eect rendered practically ml. ByA my invention Iam' enabled to overcome this objection, the clutch connecting one of the dynamo-electric machines to its load being always so energized that the slipping will take scribed.

wheels, thereby substituting for the small bearing-surface between the wheels and the rails the large bearing-surface of the clutch and permitting the machine, which is yieldably connected to its load, to operate as a generator at a lower speed than the other machine or even as a motor driven in the reverse direction, but always so restrained that its speed as a motor cannot rise above a predetermined limit. WVith such an arrangement of apparatus it is manifest that means should be provided by which the clutch will rigidly attach its motor to the axle whenever current is supplied from the power-circuit to the dynamo-electric machines operating as motors. This I prefer to do by introducing the magnetic clutch into the main motor-circuit after the last or short-circuiting point of the resistance commonly employed, so that whenever current is supplied from the trolley to the motors the clutch will be held with sufficient power to insure a rigid attachment. The power consu med in this way is practically-negligible.

Referring to the accompanying drawings, illustrating my invention, Figure l is a plan View of a car-truck, showing the motors and controllers and a clutch all arranged as de- Fig. 2 is a side elevation of the clutch, the car-axle being shown in cross-section. Fig. 3 is a section on the line 3 3 of Fig. 2. Figs. 4 and 5 are diagrams illustrating the circuit connections, and Figs. (5 and 7 are diagrams illustrating controllers adapted to m ake the circnitconnections shown in Figs. 4 and 5.

In the mechanical figures, A is the frame of the truck, of which B B are the Wheels, and C C are the controllers, and M M2 the motors. D is the clutch connecting the motor M2 to its axle through the pinion F and gear E.

In Figs. 2 and 3, H is the shaft or axle, and E the gear loosely mounted on said axle, a collar e limiting the end play. The electromagnetic member D ofthe clutch is provided with the usual coils G and collector-rings CZ d, by which the coils are included in circuit in any desired manner, and the said member is capable of longitudinal motion along the shaft H, but is held from rotation with respect to the shaft by means of keys engaging slotsin the shaft and magnetic member. The operation of these parts is as follows: W'nenever current is caused to flow in the coils G, the disk I) is magnetized and attracts the gear E, so that the pinion F (see Fig. l) in rotating the gear also rotates the axle I'I. It is manifest that by the regulation of current in the `coils G the attraction between the members of the clutch lnay be made as great as desired, either strong enough to revolve the axle at full speed or of such amount as will permit any desired slip.

In Fig. 4 I show the circuit connections which are employed when the dynamo-electric machines are operated as braking-generators. In this ligure, M M2 are the motors, and D the clutch. R represents the resistance usually employed for regulating the entire output of the dynamo-electric machines, and R a resistance shunted around the magnetic clutch, this latter resistance being made regulable, so that the cnrrentflow in the clutch maybe adjusted independently of the total dow in the circuit of the dynamo-electric machines. It is manifest that as the shunt around the magnetic clutch may be regulated from open circuit to short circuit the attraction of the latter may be varied within wide limits.

In Fig. 5 I show the circuit connections when the dynamo-electric machines are operated as motors with current supplied from the trolley connection. When thus operai'.- ing, the current passes from the trolley T through the regulating resistance R and the clutch D directly to the motors and thence to ground, it being understood that whenever the motor with which the clutch is associated is supplied with current the current passes through the clutch, so as to maintain a rigid mechanical connection of the motor with its axle.

It is manifest that the arrangement shown in Fig. 4 may be operated according to varions methods to produce the desired effects. For example, the resistance R' may be xed in value or it may be made regulable, the same as the resistance R, or it may be entirely omitted. Also when the resistance R' is made regulable the resistance R may be fixed in value, or both resistances may be simultaneonsly or successively Varied, the only essential being that the clutch shall always be so energized that its members will begin to slip on each other before the torque of the motors operating as generators becomes great enough to cause the wheels to skid and slip along the rails.

In Figs. Gand 7 I haveillustrated diagrammatically the switches and circuit connections necessary t'or the carrying out of certain of the methods above specified, the changes necessary to adapt the system to the other methods mentioned being obvious to one skilled in the art.

Referring to Fig. (3, K represents the powerswitch, RS the reversing-switch, and B the brake-switch, of a controller ot' the ordinary type, the contacts being shown developed on a plane surface, as is customaryin diagrammatically illustrating such a structure. M and M2 indicate the motors, which in the power position of the controller are operated to drive the car and in the braking position of the same are operated as braking-generators to bring the car to rest. D is the mag- IOC IIO

netic clutch by means of which the second motor M2 is connected to its car-axle. R is a resistance, which in the power position of the controller is used as a regulating resistance in series with the motor-circuits and in the braking position as a shunt to the energizing-windingof the magnetic clutch. The several switches of the controller comprise each one or more sets of fixed contacts and one or more sets of contacts movable with respect thereto, the movable contacts being ordinarily mounted upon a cylindrical surface` and brought into contact with the corresponding fixed contacts by the revolution ot the cylinder. As shown in Figs. 6 and 7, the small circles indicate the fixed contacts of the several switches, the adjacent rectangles indicating the corresponding movable contacts. The power and reversing switches are each provided with a single set of fixed contacts 5 but the brake-switch has two such sets, one comprising the contacts 19' to 24:', engaging in the braking position of the controller with the movable contacts 19b to 24h, and the other comprising contacts 25' to 34', engaging in the off position of the brake-switch with the movable contacts 25:L to 33a and in the operative position of said switch with the movable contacts 25b to 341. Interlocking devices are provided, as is customaryin the art, so that the power-switch cannot be operated unless the brake-switch is in its oft' position nor the brake switch operated unless the power-switch is in its off position and so' that the reversing-switch cannot'be operated unless both the other switches are in their off positions.

being in its ofi position, as shown, and the reversing-switch RS having been thrown to the left, so thatits contacts d willengage with the corresponding fixed contacts 1l' to 18',cur rent entering from trolley T will pass through fixed contact 1' to the movable contact 1, thence through the cross-connected contact 2 to fixed contact 2' and conductor 2, through the resistance R to the conductor 7, through the magnetic clutch Dto the fixed contact 25' on the brake-switch, thence by way of crossconnected contacts 25 and 29 of said switch and through conductor 14 to fixed contact 14' of the reversing-switch, through one of the contacts c tofixed contact 13', through motor-armature A', thence by way of conductor 12 to fixed contact 12 of the reversingswitch and through another contact a of said switch to fixed contact 11', by way of wire 1l to fixed contact 32 on the brake-switch, and by way of cross-connected contacts 32a and 33tv ot' said switch to contact 33', thence through the field-winding F of the motor M' to the conductor 9, fixed contact 9' of the power-switch, and through cross-connected contacts 8a and 9n of said switch to fixed contact 8', by way of Wire 8 to fixed contact 18' of the reversingswitch, through contact a ot' said switch to fixed contact 17', thence through the armature A2 of the motor M? to wire 16, fixed contact 16', contact c of the reversing-switch, fixed contact 15' by way of wire 15 to fixed contact 27- of the brake-switch, and by way ot' cross-connected contacts 26iv and 27WA of said switch to contact 26', through field-winding F2 of the motor M2 by way of wire 10 through the fixed contact 10' of the power- With the power-switch K in its first operative position, the brake-switch B switch to the movable contactlO, and thence to ground. In this position it will beseen that the magnetic clutch is included in the motor-circuitbetween the last resistance step and the armature 'of the first motor, so that whatever may be the position of the powerswitch of the controller the said clutch will always be energized to hold its motor fixed to the corresponding car-axle. The circuit for this position ot' the controller is indicated again inserted, and finally to again cut out* 'this resistance, the circuits for the subsequent positions of-the power-switch will not be traced. In the multiple position of the power-switch the clutch is included in the circuit of'one of the motorsonly.

Assuming that the car is in operation and that it is desired to bring the same to rest, the power-switch K will be thrown to its off position and the brake-switch B thrown on, the reversing-switch RS remaining in thesame position as before. In the first position of the brake-switch the circuit connections may be traced as follows: Starting from the plus-brush of the armature A', Fig. 6, the circuit leads by Way ot conductor 13 to the fixed contact 13' of the reversing-switch, thence to fixed contact 14' of said switch and by way of conductor 14 to fixed contact 29' of the brake-switch, through cross-connected contacts 29b and 30h of said switch to fixed contact 30', thence to conductor 7, where the circuit divides, one branch leading through the magnetic clutch D and the fixed contact 25' of the brake-switch to the movable contact 25" and the other leading also from the conductor 7 through conductor 19 and fixed contact 19 to Contact 191 and by way of cross connection to contact 25h. From contact 25b the circuit leads through contact 26", connected thereto, to fixed Contact 26', thence through the fieldwinding F2 of the-motor ML to fixed contact 28', through cross-connected contacts 271 and 28b to fixed contact 27', by way ofk conductor 15 to fixed contact15'ofthereversingswitch,thence to fixed contact 16' and by way of conductor 16 to and through the armature-winding A2 of motor M2, thence by way of wire 17 to fixed.

switch the two motors are therefore connect ITO ed in series with each other and with the magnetic clutch, the latter being shunted by a circuit of practically negligible resistance uniting its terminals, the connectionsdifering from those shown in Fig. 4; only in that no resistance is inserted directly in the m0- tor-circuit. In this position of the brakeswitch the first machine M', operating as a generator driven by the car-axle, to which it is rigidly connected, supplies current to the second machine M2, which is practically disconnected from its axle, and causes it to revolve as a motor in a direction opposite to that in which it would be driven by its axle if the magnetic clutch were energized. It the controller is maintained in this position, the second machine will rise in speed, opposing a continually-increasing counter electromotive force to the first machine, operating as a generator, until finally the current in circuit will be reduced to an amount which is just sufficient to operate the second machine as a motor running light. As the brake-switch is moved toits second position, however, a section of the resistance R is shunted around the magnetic clutch, and in the subsequent positions of the brake-switch this resistance is increased by the addition of other sections until in the final position of the brake switch the shunt-circuit around the magnetic clutch is opened and the entire current generated passes through the same. The current supplied to the magnetic clutch is therefore gradually increased as the brakeswitch is moved from its initial to its final position, and the magnetic clutch is in consequence energized more and more, thereby resisting more Vand more the tendency of the second machine to operate as a motor and tending to drive it in the opposite direction asa generator until finally when the brakeswitch is in its final position and the shuntcircuit around the magnetic clutch is opened both machines will operate as generators at the same speed unless the torque is excessive, in which case the members ot' the clutch will still continue to slip. l

The operation of the brake-switch in inserting resistance in shunt to the energizingwinding of the magnetic clutch is as follows: As the switch is moved from its first to its second position the circuit through the conductor 19 and the contacts 19 and 19h is opened, so that the current generated must fiow either through the magnetic clutch D to the contact 25b of the brake-switch or else through the first section of the resistance R tothe conductor 6, and thence by way of "conductor 2O and contacts 20' and 2Ob and the cross connection to contact 25h. In the third position a second section of the resistance R is similarly inserted, and so on, until in the final position this branch circuit around the magnetic clutch is entirely opened.

In Fig. 7 I have shown another system for carrying out my invention in which there are employed two resistancesR and R', the one being directly in the motor-circuit and the other capable of being shunted around the magnetic clutch. The system illustrated in this figure is otherwise the same as that shown in Fig. 6. In this figure, supposing the power-switch K to be in its off position and the reversing-switch RS to be so thrown as to bring the contacts a under the tixed contacts 11' and 18', the brake-switch B in its first position makes the following circuit connections: Starting from the plus brush of the armature A' of the motor M the circuit leads through contacts 13' and 14' of the reversing-switch to the conductor 14 and by way of fixed contacts 35 and 36 and crossconnected contacts 35b and 36" of the brakeswitch to conductor 7, thence through the entire resistance R to conductor 2, at which point the circuit divides, one branch leading through the magnetic clutch D and fixed contact 31 of the brakeswitch to contact 31" and the other branch leading through fixed contacts 41' and 42 and cross-connected contacts Lt1b and 42" of the brake-switch to conductor 19, thence by way of fixed contact 19', movable contact-19h, and cross connection to contact 31". From this point the circuit leads through contacts 32b and 32', through the field-winding F2 of the motor M2 to conductor 10, thence by way of contacts 33 and 3l' and cross-connected contacts 331 and 34" to conductor 15, through contacts l'and 16' of the reversingswitch to conductor 16, thence through the armature A"l of the motor M2 and by way of conductor 17 and contacts 17 and 18 of the reversing-switch to conductor 8, thence through contacts 39' and 40' and cross-connected contacts 39 and 40 of the brake-switch through the field-winding F' of the motor M' to conductor 9, through contacts 37' and 38 and cross-connected contacts 37b and 38 of the brake-switch to the conductor 11, and through contacts 11' and 12' of the reversing-switch to conductor 12 and to the minus brush of the armature A'. The two motors are thus connected in series with each other and with the magnetic clutch D, the resistance R' being also included in circuit and the terminals ot the magnetic clutch being shunted by a circuit of practically negligible resistance. The circuit connections for this position of the brake-switch are shown in Fig. 4. In this position the first machine operating as a generator' will tend to drive the second machine as a motor, the system differing from thatshown in Fig. 6 only in that the current in the circuit of the two dynamo-electric machines is limited by the resistance R',as Well as by the counter electromotive force of the second dynamo-electric machine operating as a motor. In the second position of the brakeswitch the contact 19b leaves its correspond ing contact 19', and the first section of the resistance R is thereby shunted around the terminals of the magnetic clutch, the shuntcircuit now passing through contactsA 20' and 20" of the brake-switch. yIn this position the IOO IIO

As the brake-switch is moved farther the re,

sistance shunted around the terminals of the magnetic clutch is gradually increased, and the resistance included directly in circuit with the dynamo-electric machines is gradually reduced, the changes in values of the two resistances taking place successively in the manner already explained, until in the final position of the brake-switch the shuntcircuit around the magnetic clutch is opened and the resistance R' entirely short-circuited, the two machines in this position sending the entire current generated through the magnetic clutch D. As before stated, it is obvious that the two systems shown in Figs. 6

Aand 7 are not the only ones by which my method of braking may be carried out; but the changes in connections required for other `modifications will be obvious to one skilled in the art. For example, the contacts on the brake-switch which control the resistance R might be omitted and this resistance controlled by a switch operated by hand, so that a certain definite portion of the resistance R might be continuallyin circuit in the braking position ot' the controller; or, on the other hand, the contacts of the brake-switch which control the resistance R might be omitted and a handswitch provided for shunting more or less resistance around the magnetic clutch D, the magnetic clutch being thus shunted in the braking position of ,the controller by a denite resistance and the resistance R' being varied to produce the desired variations in braking; but whatever the details of the system it will be seen that I have provided a means for so graduating the braking effect on an electric car or similar load that it may be brought to rest by a force which is gradually and uniformly increased, the system being so organized that the wheels of the car will never slip along the track in braking.

The novel method of braking a moving load disclosed in this application I do not claim herein, since it constitutes the subject-matter of aseparate application, Serial No. 99,065, iiled March 20, 1902.

What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination in an electric braking system, a moving load, a dynamo-electric machine, a yieldable clutch for connecting said machine to said moving load, and means for so connecting the electrical circuits of said machine that it will operaie to retard the movement of the load.

2. In combination in an electric braking system, a moving load, a dynamo electric machine, an electrically-actuated clutch for connectingsaid vmachine to said moving load, means for so connecting the electrical circuits of said machine that it will operate to retard the movementof the load, and means for regulating the action of said clutch.

3. In combination in an electric braking system, a moving load, a dynamo-electric machine, an electrically-actuated clutch for connecting said machine to said moving load, and electrical conductors connecting the windings of said machine and said clutch in a closed circuit.

4. In combination in an electric braking system, a moving load, a dynamo-electric machine,.an electrically-actuated clutch for connecting said machine to said moving load, electric conductors connecting the windings of said machine and said clutch in a closed circuit, and means for regulating the action of said clutch.

5. In combination, in an electric braking system, a dynamo-electric machine connected and arranged to operate as a momentumdriven generator, an electrically-actuated clutch connecting the said machine to itsload, and means for regulating the action of said clutch withgut materially affecting the potential at the terminals of the dynamo-electric machine.

6. In combination, in an electric braking system, a dynamoelectric machine connected and arranged to be operated as a generator driven by the momentum of its load, an electrically-actuated clutch connecting said machine to its load, electric conductors connecting the machine and the clutch-actuating winding in a closed circuit, and means for varying the volume of` current supplied to the clutch-actuating winding without materially affecting the potential at the terminals of the said dynamo-electric machine.

7. In combination in an electric braking system, a dynamo-electric machine, an electrically-actuated clutch connecting said machine toits load, electrical conductors connecting said machine and said clutch in a closed circuit, and means for shunting said clutch.

8. In combination, a dynamo-electric ma- ICO lIO

chine, an electrically-actuated clutch concrater.

'clutching means when said machines are oping the power transmitted by said clutch when said machine is operating as a braking-gen- 10. In combination in an electric braking system, two or more dynamo-electric machines, an electrically-actuated clutch connecting one of said machines to its load, and electric cond uetors connecting said machines in series with each other and with said clutch.

11. In combination in an electric braking system, two or more dynamo-electric machines, an electrically-aetuated clutch connecting one of said machines to its load, electric conductors connecting said machines in series with each other and with said clutch, and means for regulating the action of said clutch.

12. In combination in an electric braking system, two or more dynamo-electric machines, an electrically-actuated clutch connecting one of said machines to its load, electric conductors connecting said machines in series with each other and with said clutch, and means for shunting said clutch.

13. In combination, two or more dynamo-electric machines, electrically-actuated clutching means connecting some of said machines to a load, a rigid connection between the other of said dynamoelectric machines and said load, means for locking said erating as motors to drive the load,and means for regulating the action of said clutching means when said machines are operating as brakes to retard the load.

14. In combination, two or more dynamo-electric machines, electrically-actuated clutching means connecting some of said machines to a load, a rigid connection between the other of said dynamo-electric machines and said load, means for locking said clutching means when said machines are operating as motors to drive the load, and means forW limiting the power transmitted by said clutching means when said machines are operating as brakes to retard the load.

15. In combination in an electric braking system, a dynamo-electric machine, an electrically-actuated clutch connecting said machine to its load, electrical conductors connecting said machine and said clutch in a closed circuit, means for regulating the flow of current in said circuit, and means for shunting said clutch.

16. In combination in an electric braking system, two or more dynamo electric machines, an electrically-actuated clutch conreason neeting one of` said machines toits load, electrical conductors connecting said machines in series with each other and with said clutch, a resistance included in the main circuit of the dynamo-electric machines, a resistance in shunt to the clutch, and means for gradually increasing the shunt resistance and decreasing the resistance in the main circuit.

17. In combination, in an electric braking system, a dynamo electric machine operatively connected to a moving load so that the said machine will be driven as a generator by the momentum of the load, a second dynamo-electric machine electrically connected in circuit with the first, and means for gradually clutching the second machine to theload.

18. In combination, in an electric braking system, a dynamoelectric machine operatively connected to a moving load so that the said machine will be driven as a generator by the momentum of the load, a second dynamoelectric machine electrically connected in eircuit with the first, a clutchconnecting said second machine to the moving load,and means for regulating the power transmitted by the clutch.

19. In combination, in an electric braking system, a dynamoelectric machine operatively connected to a moving load so that it will be driven as a generator by the momentum of its load, aseconddynamo-electric machine connected in circuit with the first, an electrically-actuated device for clutching the second machine to the same load, said clutch having its actuating-windings included into circuit with said machines, and means for diverting from the clutch-actuating Winding, more or less of the current generated.

20. In combination, in an electric braking system, a dynamo-electric machine operatively connected to a moving load so that it will be driven as a generator by the momentum' of its load, a second dynamo-electric machine connected in circuit with the first, an electrically-actuated device for clutching the second machine to the same load,said clutch having its actuating-windings included into circuit with said machines, means for controlling the How of current in the circuit of said machines, and means for diverting more or less of said current from the clutch-actuating winding.

In witness whereof I have hereunto set my hand this 16th day of February, 1900.

FRANK E. CASE.

fitnessesz BENJAMIN B. HULL, JOSEPH Gltoss.

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